The administration of glutamic acid or succinic acid (which is found in the citric acid cycle) terminated the mental symptoms induced by LSD. Succinic acid also temporarily relieved the acute symptoms of schizophrenia. It is possible that in schizophrenia and in the condition induced by LSD there is a disturbance of carbohydrate metabolism in certain circumscribed areas of the brain (similarity of symptoms; effectiveness of minimal doses of LSD), possibly in the posterior hypothalamus. The latter is involved in the change-over between the waking and dreamy states which is disturbed in schizophrenia. It is of interest that patients with damage to this region of the brain were resistant to 10-40 mcg. LSD.